Synthesis and separation of the atropisomers of 2-(5-benzo[ b]fluorenyl)-2′-hydroxy-1,1′-binaphthyl and related compounds

Abstract

Several syn and anti atropisomers of 2-(5-benzo[ b]fluorenyl)-2′-hydroxy-1,1′-binaphthyl and related compounds were synthesized from 1,1′-binaphthyl-2,2′-diol (BINOL). It was possible to separate the syn and anti atropisomers by silica gel column chromatography. The syn atropisomers are potential hetero-bidentate ligands for complex formation with metals. By starting from enantiomerically pure ( R)-(+)-BINOL and ( S)-(−)-BINOL, four optically active syn atropisomers and two anti atropisomers with high enantiomeric purity were obtained. The structures of two syn atropisomers and one anti atropisomer were established by X-ray structure analyses.